Constant delivery pump



Dec. 29, 1 10 P. ANDERSON ETAL 3,551,077

CONSTANT DELIVERY PUMP Filed Oct. 16, 1968 "H w m INVENTORS Perry Anderson Walther Rich/er Dona/d FK/e/h/re L r ATTORNEY United States Patent US. Cl. 417-415 7 Claims ABSTRACT OF THE DISCLOSURE A constant delivery pump including a cylindrical rotor mounted for rotation in a housing bore and provided with successive first and second sections defining communicating pump and eccentric chambers. A reciprocatory piston is spring-biased into engagement with the eccentric cam surface of the second section and is operable to periodically pump a given quantity of liquid into the delivery outlet passage of the housing for each revolution of the rotor. During the suction cycle, the piston is displaced outwardly to increase the size of the eccentric chamber to a maximum, and during the pumping cycle, the piston is displaced inwardly to reduce the size of the eccentric chamber to a minimum. When the back pressure exceeds the spring pressure, the reciprocation of the piston is interrupted, and the rotor runs in an idle unloaded condition.

This invention relates to an improved constant delivery pump of the type including a cylindrical rotor having an eccentric cam section for driving a reciprocatory piston to increase the size of the pump chamber to a maximum during the suction stroke, and to reduce the size to a minimum during the pumping stroke. Similar pumps are known in the art as evidenced by the US. patents to Reis No. 3,302,576, Gutkowski No. 3,285,192 and Crossman No. 2,363,119.

In the known constant delivery pumps, various drawbacks aifecting efficient pump operation are the deleterious leakage that occurs around the rotor member, the stalling or overloading of the drive motor that occurs when the delivery of the pump is blocked, and the cost of machining and producing the pump components, together with the necessity for auxiliary equipment, such as check valves and the like. The present invention was developed to provide an improved constant delivery pump that avoids the above and other drawbacks of the known pump means.

The primary object of the present invention is to provide an improved constant delivery pump having a cylindrical rotor provided with a pumping section and an eccentric section defining communicating pumping and eccentric chambers, respectively, said eccentric section being operable to reciprocate a radially arranged plunger to periodically vary the size of the eccentric chamber to effect pumping of the liquid.

A more specific object of the invention is to provide a constant delivery pump of the type described above, wherein the pumping and eccentric sections are arranged between a pair of cylindrical support sections that are journalled with a close tolerance fit in a corresponding bore in the pump housing.

In accordance with a more specific object of the invention, the pump pressure is determined by the biasing force of the spring means that urge the piston into engagement with the eccentric cam surface of the rotor. In the event that the outlet conduit is blocked and the back pressure exceeds the spring biasing force, the reciprocatory movement of the piston is terminated and the motor runs idle. Consequently, the designer has com- Patented Dec. 29, 1970 ICE.

plete control over the maximum pressure delivered by the pump, and can effect desired pressure variations by the appropriate substitution of springs.

Other objects and advantages of the invention will become apparent from a study of the following specification, when considered in the light of the accompanying drawing, in which:

FIG. 1 is a cross-sectional view of the constant delivery pump; and

FIGS. 2 and 3 are sectional views taken along lines 2-2 and 3-3 of FIG. 1, respectively.

Referring now to the drawing, the constant delivery pump includes a housing 2 containing a cylindrical through bore 4 in communication with diametrically opposed inlet and outlet passages 6 and 7, respectively. Rotatably mounted in the. bore is a rotor 8 having, in succession, a generally cylindrical first section 8a containing a recessed flat face 10 defining a pump chamber 12, and a cam section 8b of cylindrical configuration laterally offset from the axis of the rotor (as shown in FIG. 3), to define an eccentric chamber 14 in communication with the pump chamber 10. On opposite sides of these two sections are a pair of cylindrical support sections each having a diameter generally equal to the diameter of bore 4. The rotor includes finally an upper flange portion 8d adapted for seating engagement with the upper surface of the housing, and an upwardly extending stub shaft 8e adapted for driven connection with the constant speed drive motor 16 via flexible coupling 18. Opposite the cam section 8b, the housing 2 contains a radial bore in which is slidably mounted the reciprocatory piston 20. The piston is biased inwardly toward engagement with the cam section 812 by means of a generally U-shaped leaf spring member 22 that is mounted by one leg on discharge conduit 24 between the lock nuts 26 and 28.

OPERATION Assume that the motor 16 drives the rotor at a constant speed in the direction indicated by the arrow in FIG. 2. Liquid, such as water or the like, is drawn through inlet 6 into the pump chamber 12 and upwardly into the eccentric chamber 14. During further rotation from the position indicated in FIG. 3, the plunger 20 is displaced outwardly against the biasing force of spring 22 by the cam section 8b, whereby the volume of the eccentric chamber 14 is increased to a maximum. The trailing edge of the flat face 10 then closes the inlet passage 6 to isolate the supply from the pump chamber 12.

Upon further rotation of the rotor, the leading edge of the flat face 10 reaches a position opposite the discharge passage 7, whereupon pump chamber 12 and eccentric chamber 14 communicate with the discharge conduit 24 via outlet passage 7. During this time, plunger 20 is displaced inwardly (because of the corresponding contour of the cam section 8b), whereby the volume of the eccentric chamber is reduced to pump a given constant quantity of the fluid from eccentric chamber 14 to discharge pipe 24 via chamber 12 and outlet passage 7.

Preferably the housing, rotor and piston are formed of brass, and the spring is formed of beryllium copper, although other appropriate materials may be used, if desired. With constant input speed, a constant delivery of liquid is achieved, the maximum pump pressure being determined by the amount of force that the spring exerts on the plunger. The volume of the pumped liquid is determined -by the diameter of the plunger and the length of its stroke, as determined by the eccentricity of the cam surface of section 8b. Consequently, with each revolution, a volume equal to the plunger displacement is delivered to the delivery conduit 24.

It is important to note that in accordance with the advantageous construction of the present invention, the plunger or piston is operated by cam means within the pressure system, so that if leakage is held to an absolute minimum, a constant volume is delivered with each revolution. Furthermore, as distinguished from conventional constant delivery pumps wherein the drive motor is stalled or becomes severely overloaded when the pump output is blocked, in the instant invention, upon blocking of the output, the reciprocatory motion of the plunger is interrupted and the motor runs idle. More particularly, when the back pressure exceeds the biasing force of spring 22, during the suction stroke liquid is drawn into pump cavity 12, but when the inlet port is sealed and the outlet port is opened, the back pressure in chambers 12 and 14 exceeds the biasing force of spring 22, whereby piston 20 remains in its outwardly displaced inactive position.

The pump is of inexpensive construction in that complicated machining procedures and close tolerances are avoided. In the housing, only a straight cylindrical bore and an orthogonally arranged bore are required, and the size and position of the inlet and outlet ports are not critical. The rotor is machined first for proper diametrical fit in the housing, and then the cam and flat faces are machined thereon. Therefore, the only critical dimensions on the pump are the diameter of the bore and the diameter of the rotor, thereby resulting in the inexpensive production of the components.

While in accordance with the provisions of the patent statutes the preferred form and embodiment of the invention has been illustrated and described, it will be apparent to those skilled in the art that various modifications and changes may be made without deviating from the disclosed inventive concepts.

What is claimed is:

1. Constant delivery pump means, comprising a housing (2) containing a cylindrical first bore (4);

a rotor (8) rotatably mounted in, and having substantially the same diameter as, said bore, said rotor including, in longitudinally arranged relation, successive contiguous first (8a) and cam (8b) sections, respectively, said first section being generally cylindrical and containing a first recess having a flat recessed face (10) parallel with and spaced from the rotor axis, said first section having in transverse cross-section an area greater than one-half the crosssectional area of said bore, said first recess cooperating with the wall of said housing bore to define a pumping chamber (12), said cam section containing a second recess having a cam surface generated by the displacement of a line parallel with said rotor axis along a path eccentric to said rotor axis, said second recess cooperating with the wall of said housing bore to define an eccentric chamber (14) in constant communication with said pumping chamber;

said housing containing also inlet and outlet passages 4 (6, 7) having valve ports arranged relative to said first rotor section for alternate communication with said pumping chamber, respectively, and a transverse through bore extending radially from said first bore opposite said cam rotor section;

a piston mounted for reciprocation in said transverse bore; and

spring means biasing said piston radially inwardly toward engagement at one end with the eccentric cam surface of said cam section, whereby upon rotation of said rotor, the effective volume of the pumping chamber progressively increases and decreases to pump fluid from said inlet passage to said outlet passage.

2. Pump means as defined in claim 1, wherein said rotor includes on opposite sides of said first and cam sections a pair of cylindrical support sections the diameter of which is generally equal to that of said bore.

3. Apparatus as defined in claim 2, wherein the ports of said inlet and outlet passages are arranged in diametrically opposed relationship on the bore wall.

4. Apparatus as defined in claim 3, wherein the cam section is cylindrical.

5. Apparatus as defined in claim 4, wherein the axis of the cam section is so arranged relative to said planar surface that the piston is displaced outwardly during the time the pump chamber is in communication with said inlet passage.

6. Apparatus as defined in claim 5, and further wherein the cam section is so arranged that the piston is displaced inwardly during the time the pump chamber is in communication with aid outlet passage.

7. Apparatus as defined in claim 5, and further including constant speed motor means driving said rotor, said spring exerting such a pressure on said piston that when the outlet passage is blocked, the reciprocatory motion of said piston is interrupted.

References Cited UNITED STATES PATENTS 1,382,336 6/1921 Behr 103227 2,111,000 3/1938 Moulet 1031l6 2,188,003 1/1940 Gates 103-123 2,910,947 11/1959 Nicholas 103123 3,079,867 3/1963 Thomas 103l23 3,168,872 2/1965 Pinkerton 103-157 3,314,368 4/1967 Prutchas et al 103123 FOREIGN PATENTS 241,999 11/1925 Great Britain 103-123 WILLIAM L. FREEH, Primary Examiner 7 US. Cl. X.R. 417437, 471, 519 

